1. Field of the Invention
This invention relates to a wire for reinforcing rubber goods, and more particularly to provision of a brass plated wire of the aforesaid type made by a thermal diffusion process and having a highly improved adhesion with rubber.
2. Description of the Prior Art
Recently, with the progress of various composite materials, research and development of materials having new physical properties have been carried out. Especially, among metallic materials having a very high strength and a high rigidity, wires such as steel wires, steel stranded wires, and steel cores having flexible and resilient rubber adhered thereto have been developed as new materials having excellent static and dynamic elongation and flexing fatigue resistivity, these new materials have made a remarkable contribution to automobile rubber tires, rubber hoses, and other industrial products as well as in other fields. Generally speaking, there are two basic methods for adhering rubber onto the surface of a metal; i.e., a process for applying chlorinated rubber, cyclized rubber, synthetic resin or isocyanates on the surface of the metal for facilitating the adhesion of rubber thereto, and another process for plating brass or other suitable material on the surface of the metal for improving the adhesion of rubber thereto. The latter method is better in heat-resisting adhesion and flexure resisting properties than the former method, so that it is well known that the latter method has been generally used.
For high-level requirements as represented by those necessitated by high-speed and other advanced performance of recent automobiles, however, the adhesion of the conventional brass plated steel cords with rubber is insufficient, and there is a demand for further reduction of variation in adhesion. To meet such demand, various trials have been made, such as a process of applying an additional adhesive liquid on the brass plated steel cords and a process using a modified formula of compounding agents for rubber. Those recent trials, however, have not succeeded yet in providing satisfactory adhesion of a metal with rubber through a simple process.